Method of producing alkyl esters of abietic acid



Patented Mar. 4, 1930 UNITED STATES PATENT OFFICE ALAN C. JOHNSTON, OF KENVIL, NEW JERSEY, ASSIGNOR TO HERCULES POWDER COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE METHOD OE PRODUCING AL KYL E STERS F ABIETIC ACID No Drawing. Original application filed October 18, 1927, Serial No. 227,042. Divided and this application filed June 12, 1928.

My invention relates to the production of alkyl esters of resin acids, and more particularly contemplates the production of alkyl esters of abietic acid through the use of alkyl halides.

In carrying out the process embodying my invention the alkyl esters may be produced by the esterification of resin acids in a pure state or as found in resins and by virtue of my invention the esters may be prepared, for example, from ordinary Wood rosin or from a resin, for example, containing pimaric acid.

According to my invention, for example, abietic acid or rosin is subjected to treatment with an alkyl halide,f0r example, an alkyl chloride such as eth l chloride, amyl chloride, etc., or an alky bromide, as ethyl bromide, butyl bromide, etc., in the presence of an alkali, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, etc., the

alkali preferably being in'solution in alcohol. The treatment of the abietic acid, or of rosin, in accordance with my invention is carried out at temperatures enabling refluxing and may be carried out under atmospherie of increased pressure depending upon the alkyl halide used.

The process according to my invention more particularly involves the heating of abietic acid, or other resin acid, pure or as found in rosins or in resins, and an alkyl halide and sufficient alkali for neutralizing the abietic acid with the formation of a halide of the alkali and the alkyl abietate. The

reaction is preferably carried out in the presence of a solvent, as an alcohol, which will dissolve both the alkyl halide and the inorganic abietate. When the reaction between the inorganic abietate, e. g. sodium resinate,

40 and the' alkyl halide'is complete, the inorganic halide formed is filtered olf,'the alcohol removed by distillation and the ester subsequently distilled off under reduced pres sure. Any excess of thealkyl halide is recovered with the alcohol, both of. which may be reused. I

As examples of the carrying out of the process embodying y invention the follow ing will be illustrative:

In the production, for example, of ethyl Serial No. 284,877.

about 150 .160 C. The reaction is as follows:

wHaCOONa C2H5C1= When the reaction, which. Will require about one-half hour, is complete the sodium chloride which has beenformed is filtered out, the alcohol distilled off, and the ester, thyl abietate, distilled under reduced pressure. Any excess of alkyl chloride and the alcohol are recovered and may be reused.

As a result of the carrying out of the process as given in the above example a yield of about'270 parts of ethyl abietate having an A. N. of 5 is obtained. If it is desired to obtain a product having a lower A. N., such can be obtained either by redistillation of the ester from a small amount of soda ash or by adding soda ash to the crude product, from which the ester is originally distilled,

prior to the distillation off of the ester.

As a further example of the carrying out of the process involving my invention, for example, for the production of n-butyl abietate, 20 g. of sodium hydroxide are dissolved in 20 cc. of water and 200 parts of ethyl alcohol added. To the solution formed 150 g. ofrosin and 100 g. of butyl bromide are added and the whole refluxed for a period of six hours. When the reaction is complete the alcohol may be distilled off and then about 95 g. of n-butyl abietate, A. N. 6, may be recovered by distillation under reduced pressure.

-As a further exam Ie, the n-amyl abietate may be prepared byorming a solution of 60 g. of sodium hydroxide and 750 parts of alcohol, then adding to the solution 450 parts of rosin and 200 parts of normal amyl chloride. The solution formed after bein heated in an autoclave at say about 150 .-160 0., pressure about 160. pounds, for about one 100 hour and distillation off of the alcohol will yield by distillation under reduced pressure about 353 parts of n-amyl abietate A. N. 5. The n-amyl abietate will distill within the range of about 240 C.250 C. under 5 mm. pressure. Mixed amyl chloride, or a mixture of alkyl chlorides, e. g. butyl, amyl and hexyl chlorides may be converted into alkyl abietates in a similar manner.

It will be noted that in the carrying out of the process embodying my invention the abietic acid, or resin acid, is substantially neutralized by treatment with an alkali, forming an inorganic salt of the abietic acid, or other resin acid. As the alkali I prefer to use sodium hydroxide, but it will be understood that potassium hydroxide, sodium carbonate, calcium hydroxide, etc. may be used.

It will be noted in accordance with my invention that the production of abietates or esters of abietic acid, which may be relatively pure, or as found in rosin, may be prepared through the use of alkyl halides such as the alkyl chloride or the alkyl bromide. In addition to the methyl and ethyl esters of abietic acid the n-propyl, isopropyl, n-butyl, isobutyl and isoamyl esters may be produced. Further, in accordance with my invention I have discovered the practicability of producing normal amyl abietate throu h the use of an amyl. halide, a compound w ich has not heretofore been known.

It will be understood that while I have described the application of my invention more particularly to the production of abietates, that my invention is applicable to and contemplates the treatment of other resin acids as, for example, pimaric acid.

This application-is filed as a division of the application filed by me October 18, 1927, Serial No. 227,042.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is 1. The method of producing the amyl ester of a resin acid, which includes the step of treating a resin acid with an amyl halide in the presence of'an alkali.

2. The method of producing the amyl ester of abietic acid, which includes the step of treating abietic acid with an amyl halide in the presence of an alkali.

3. The method of producing the amyl ester of abietic acid, which includes heating a solution of abietic acid, an alkali and an amyl halide.

4. The method of producing the amyl ester of abietic acid, which includes subjecting abietic acid to treatment with an amyl halide in the presence of alcohol and an alkali.

5. The method of producing the amyl ester of abietic acid,'which includes subjecting sodium abietate to treatment with an amyl halide and distilling olf the ester formed.

6. The method of producing the amyl ester of a resin acid, which includes subjecting a resin to treatment with an amyl halide and alkali in the presence of a solvent for both the amyl halide and the inorganic salt of the resin acid, separating the alkali halide formed from thesolution of the ester formed and distilling oil the ester.

7. The method of producing the amyl ester of abietic acid, which includes subjecting sodium abietate to treatment with an amyl halide in the presence of a solvent for both the amyl halide and sodium abietate, separating the alkali halide formed from the solution of the ester formed and distilling oil the ester under reduced pressure.

8. The method of producing the amyl ester of abietic acid, which includes heating an inorganic salt of abietic acid with amyl chloride under pressure.

9. The method of producing the amyl ester of abietic acid, which includes heating abietic acid, an alkali and an amyl halide under pressure.

10. Themethod of producing the amyl ester of abietic acid, which includes heating abietic acid, an alkali and an amyl halide under pressure and then distilling 01f the ester formed under reduced pressure.

11. The method of producing the amyl ester of abietic acid, which includes heating sodium abietate, amyl chloride and alcohol under pressure and distilling off the ester formed under reduced pressure.

12. The method of producing the amyl ester of abietic acid, which includes heating abietic acid, an alkali, and an amyl halide under pressure in the presence of a solvent for both the amyl halide and the ester to be produced, separating the alkali halide formed from the solution of the ester formed and distilling off the ester under reduced pressure.

13. The method of producing the amyl ester of abietic acid, which includes the step of subjecting an alkali metal salt of abietic acid to treatment with an amyl halide.

14. The method of producing the amyl es 'ter of abietic acid, which includes the step of subjecting an inorganic salt of abietic acid to treatment with amyl chloride.

15. The method of producing the amyl ester of aresin acid, which includes heating a solution of a resin acid, an alkali and an amyl halide under pressure and then distilling oil the amyl ester under reduced pressure.

16. The method of producing the amyl ester of a resin acid, which includes heating a solution of a resin acid, an alkali and an amyl chloride under pressure and then dis tilling off the amyl ester under reduced pressure.

17. As a new article of manufacture the ester of abietic acid formed by the reaction between abietic acid and normal amyl halide in the presence of an alkali.

18. The method of producing an am 1 ester of the resin acid contained in woo rosin, which includes heating a solution of wood rosin, an alkali and an amyl halide.

19. The method of producing an amyl ester of the resin acid contained in wood rosin, which includes the step of treating wood rosin with an amyl halide in the presence of an alkali.

20. The method of producing an amyl ester of the resin acid contained in wood rosin, which includes subjectin wood rosin to treatment with an amyl halide in the presence of alcohol and an alkali.

21. The method of producing an amyl ester of the resin acid contained in wood rosin,

which includes heating'an inorganic salt of wood rosin with an amyl chloride under pressure.

22. As a new product the normal amyl ester of a resin acid.

In testimony of which invention, I have hereunto set my hand, at KenviLNew Jersey, on this 8th day of June, 1928.

ALAN C. JOHNSTON. 

